1. Field of the Invention
The present invention relates to a recording sheet which records by contact printing using water-based ink. More particularly, the present invention relates to a recording sheet for operating with a high degree of accuracy while, for example, recording heat treatment temperatures, recording, in high densities, phenomena which constantly change, such as wind direction, wind velocity, flow rate, electrical current or the like, recording measurements at places where temperature and humidity environment requirements are stringent, measurements of which are performed by a water gauge and a weather observation recording apparatus, recording the reading of a tap-water, gas or electricity meter, in which recording by printing is performed by means of a thermal color development system or the like, or recording fare adjustments performed inside trains.
2. Description of the Related Art
When recording is performed on a recording sheet for charts in a high humidity environment, a chart paper absorbs moisture and becomes irregular. Therefore, accurate recording cannot be performed. For this reason, plastic films, synthetic paper, or recording sheets having a coating applied on plastic films or synthetic paper are used when recording is performed in a high humidity environment. However, conventional plastic films, synthetic paper, or recording sheets having a coating applied thereon cannot be folded easily after recording is performed with a pen.
Common chart recording is performed by using a water-based pen. However, the aforesaid plastic films, synthetic paper, or recording sheets having a coating applied thereon do not efficiently absorb ink of a water-based pen. Therefore, when high-density recording is performed, water-based ink on the recording sheet cannot be absorbed and spread sideways, causing the recording to blur. In addition to this, the ink is transferred when the recording sheet is taken up or folded after recording with the water-based pen because the water-based ink is not sufficiently dried, and undried ink contacts a recording sheet fed on the ink.
To cope with this, an oil-based pen which uses an oil-based ink which dries quickly instead of a water-based pen has been used. However, the pen point of an oil pen dries easily. Thus, pen points have to be replaced frequently, and considerable labor is required. In addition, chart recording is performed on a recording sheet in a high temperature environment, irregularities are caused in a recording sheet formed of paper, and thus recording with a high degree of accuracy cannot be performed.
For this reason, plastic films, synthetic paper, or recording sheets having a coating applied thereon are used. However, they do not efficiently absorb the ink of a water-based pen, therefore an oil-based pen must be used. However, when an oil-based pen is used, solvents of oil-based ink evaporate easily in high temperatures, and thus pens have to be replaced frequently, making high-density recording impossible.
The above-mentioned plastic films, synthetic paper, or recording sheets having a coating performed thereon have unsatisfactory resistance to heat. Thus, when there are temperature changes during recording or analysis, thermal shrinkage is caused, making precise recording or analysis impossible. In addition to this, such films, paper, or sheets, have poor resistance to water, and thus if they are exposed to water, ink flows and it is difficult to read the record. In addition, for instance, winding curl is caused in a roll sheet type.
Common paper of high-grade paper wound in the form of a roll or the like is used during recording of the reading of a meter by the use of a printer or during fare adjustment.
However, since paper is wound in the form of a roll, the paper tends to curl. Also, if the paper is cut from the printer after printing, the paper curls. Thus, the work of a meterman is hindered, and the person receiving the paper must expand the curled paper to read the contents thereof. Also, when the curled paper is laminated on a record list and stored, such storing is hindered in a condition in which the paper is curled. In addition, because the paper is common paper, it has poor resistance to water, and thus the meterman must be careful not expose the paper to rain.
In addition, when the paper is used for fare adjustment inside trains, there is a problem, for example, the paper must be expanded to check it at a ticket gate or the like.